The invention concerns a pneumatic pumping device for pumping liquid.
The invention concerns more especially a pneumatic pumping device operating in a discontinuous fashion and with compressed gas such as air, and that is intended for pumping all sorts of liquids and more especially, but not exclusively, liquids such as landfill leachates, thick matter or polluted and possibly thick liquids. Within the framework of this invention, the term xe2x80x98liquidxe2x80x99 designates all these liquids indifferently.
The pneumatic pumping device of the invention is intended for working in an immersed position and for pumping up leachates and other liquids, regardless whether they are polluted and/or thick or not, from depths in the order of 50 to 60 meters. Such liquids may have a high temperature, for example in the order of 80xc2x0 C. Moreover, these liquids can be loaded with salt and transport abrasive particles such as sand, clayey smalls or sandy muds.
Most pumps existing on the market exhibit numerous shortcomings when they should be used for pumping leachates or polluted and/or thick liquids.
Indeed, engine pumps are not often explosion-proof since they operate directly on electricity; and all the known pneumatic pumps, which are explosion-proof since they are supplied with the energy produced by compressed air, comprise strainers, shutters or floaters that can be clogged or blocked regularly by the presence of mud or sludge at the bottom of the liquid pumping up wells, and by the presence of chloride deposits. Moreover, the presence of a floater or of a shutter can limit the positioning possibilities of the pump.
These problems lead to high maintenance and upkeep costs of the pumps, as well as repeated handling of the materials in spite of the toxicity risks associated with certain pumped products.
Moreover, for certain pneumatic pumps, devices associated with a floater are suggested, which trigger the air supply into the pump directly. The purpose of these pumps is to be able to control the operation of the pump directly, in relation to the arrival and to the level of the liquid. However, when the floater is blocked, the pump is not operating any longer and the pump operator cannot know whether the said pump is working, not working, or off.
Another shortcoming is the very large number of maintenance parts.
Also, in most landfills the permanent problem is the presence of plastic films floating on the surface in the leachates, which leads regularly to clogging and stopping the operation of the pumps.
Besides, it may be interesting for the landfill operator to regulate the operation of the pump according to the level of leachates or polluted liquids in the well, without running the risk of causing an explosion, for example by a spark. Indeed, the landfill wells have often now a double mission to fulfil: to enable pumping up leachates and pumping biogases.
The purpose of the invention is to provide a pneumatic pumping device that is capable of remedying the shortcomings mentioned above and that can be placed easily in a well or a pit at variable depths.
The purpose of the invention is satisfied with a pneumatic pumping device of a liquid operating in a discontinuous fashion and immersed, and with compressed gas and that is intended for pumping liquids such as landfill leachates. This device comprises a tubular body forming a pump body and defining a cylindrical main chamber in the upstream and downstream ends of which respectively emerge an inlet orifice and an outlet orifice for the liquid to be pumped.
According to the invention, the pneumatic device comprises a sleeve valve arranged in front of the inlet orifice to control the passage of the liquid to be pumped through the said orifice, means for controlling the opening and closure of the sleeve valve with a compressed gas, a delivery pipe passing through the outlet orifice and extending inside the tubular body over the major part of the length thereof, and means for supplying the main chamber with compressed gas.
The invention also concerns the following features, considered individually or in all their technically possible combinations:
The pumping device can be used in vertical position as well as in horizontal or slanted position.
This advantage is due to the fact that the device does not comprise any shutters or floaters.
The tubular body forming a pump body consists essentially of a cylindrical tube closed at both its ends, the upstream end and the downstream end, respectively with a lower plate and an upper plate, whereas the space between both these plates forms the main chamber of the pumping device, the inlet orifice of the main chamber is placed in the lower section of the tubular body, considered in the position of use of the device according to the invention and the outlet orifice is arranged in the upper section of the tubular body.
Advantageously, in view of the cylindrical shape of the tubular body as well as of the main chamber, the inlet orifice of the main chamber is situated in the lower plate of the tubular body and the outlet orifice is situated in the upper plate.
The pump body has a cylindrical revolution.
The sleeve valve is composed of a tubular body forming a secondary chamber in the upstream and downstream ends of which emerge, at each of both ends, at least one opening for the passage of the liquid to be pumped. These passage openings are connected together by an elastically ductile sleeve that constitutes a channel through the liquid to be pumped should flow to enter the main chamber of the pumping device. The sleeve separates hermetically the channel from the secondary chamber surrounding the channel.
The tubular body of the pump, the plates and the sleeve valve are made of materials resistant to thick matters, polluted liquids, salted liquids and liquids whose temperatures may be higher than 80xc2x0 C.
The pump body can be made of a material selected among the group constituted by iron, stainless steel, coated iron, elastomers, glass and carbon fibre materials, materials resisting to very high temperatures and to pressure, coated materials and alloys.
The material of the tubular body of the pump is selected so that the body can be protected by an anticorrosion coating, preventing oxidations and chloride deposits.
The sleeve valve is arranged outside, and adjacent to, the tubular body in front of the inlet orifice, and the sleeve is advantageously arranged coaxially with respect to the axis of the inlet orifice. However, the sleeve can also be offset radially. The liquid to be pumped cannot reach the main chamber as long as the sleeve valve is closed.
The inlet orifice of the main chamber and the sleeve of the sleeve valve are arranged coaxially with respect to the axis of the tubular body.
In order to control the passage of the liquid to be pumped through the inlet orifice, the space surrounding the passage channel of the sleeve valve is connected by a pipe integral with the tubular body, to a compressed gas supply source. This arrangement enables to control the closure of the sleeve valve by injecting a compressed gas in the space of the secondary chamber surrounding the channel and to choke the sleeve.
The delivery pipe going through the outlet orifice extends outside the main chamber over a distance enabling to connect the delivery pipe to a duct linking the pumping device to a collector intended for receiving the liquid to be pumped.
The delivery pipe is fitted with a return valve.
The delivery pipe extends inside the main chamber almost up the lower plate. The distance between the free end of the delivery pipe and the lower plate delineates the volume or the quantity, of liquid that remains in the main chamber at the end of the exhaust phase. A judicious selection of this distance enables total emptying of the main chamber.
The means enabling to supply the main chamber with compressed gas are advantageously composed of an opening provided in the upper plate of the tubular body, whereas the opening enables connection of the main chamber, for example by a pipe going through the upper plate of the tubular body and by any other appropriate means, to a compressed gas supply source.
At least one of the pipes among the delivery pipe, the compressed gas supply pipe of the main chamber and the compressed gas supply pipe of the secondary chamber, does not protrude from the wall of the pump body. Connection to the pipe(s) concerned is made, for example, by screw coupling(s).
The pumping device is fitted with at least one eyelet for fixing a chain, a cable or a film enabling to lower the device into a well, to fasten it and to maintain it at a determined (depth) level, to lift it and to winch it from the well. Most often, the pumping device will be provided with two eyelets, but it may obviously be fitted with more than two eyelets.
The pumping device is fitted with a protection grid or a strainer enabling to protect the sleeve valve against loads whose sizes exceed a selected limit value. This limit value or maximum template is defined advantageously by the mesh size of the grid.
The pumping system is fitted with a tripod integral with the pump body or a tripod screwed or welded to, for example by means of a foundation circular base, the pump body.
Both pipes used for connection of the compressed air supply of the pump body and of the sleeve valve, and possibly the delivery pipe as well, protrude from the pump body. In this embodiment, the connection of each of these pipes to corresponding pipes from the surface of the well or the pit, is made for example by a screw coupling, at a given distance from the upper plate of the pump body. Thanks to this arrangement, the operator has a better grip on the pump when inserting it into the well or the pit.
The pneumatic pumping device, called thereunder xe2x80x98the pumpxe2x80x99 as well, is designed to operate in an immersed fashion. So, the arrangement of the delivery pipe in the upper plate of the tubular body is advantageous since the liquid to be pumped can be emptied by a straight pipe. However, any arrangement different from the said, for instance the connection of a bent pipe to the lateral wall of the tubular body, also corresponds to the principle of this invention.
The pump operates as follows:
The secondary chamber of the sleeve valve is depressurised. Thus, the sleeve expands, the sleeve valve opens and the liquid to be pumped enters the main chamber of the pump immersed.
The level of liquid inside the pump and outside, i.e. in the well, are balanced according to the principle of communicating vessels.
When the main chamber is full, delay means (xe2x80x98timerxe2x80x99) actuate a device for controlling the sleeve valve and pressurise the said valve. Compressed air is then set in communication with the secondary chamber of the sleeve valve, which means that the pressure of the compressed air pushed the ductile sleeve back until it is choked so that the inlet orifice of the main chamber is blanked off, to prevent all liquids and sludges from entering or leaving the pump body, which isolates the liquids and sludges from the external medium of the well, in the pump body.
After a period given by the delay means, seeing to the closure of the sleeve of the valve and maintaining it in closed position, compressed air is sent to the main chamber of the body of the pump. This compressed air inrush expels the leachates and the liquids contained in the pump body, through the delivery pipe towards the surface of the well and into a collector, a tank or any other appropriate means available for receiving the pumped liquid.
When the main chamber and the delivery pipe are purged from all liquids, the sleeve valve control means depressurised the secondary chamber, which enables, on the one hand, to sleeve to expand and to release the inlet orifice of the main chamber and, in so doing, on the other hand, the pumping device to wrap around to the beginning of the cycle.
For good operation of the pump, a number of conditions must be met advantageously:
The sleeve valve is installed in the extension of the main chamber. Advantageously, the tubular body constitutes at the same time the external wall of the main chamber and that of the secondary chamber. In such an arrangement, the lower plate separates both chambers hermetically.
The passage opening of the valve is situated at a level above which the landfill or the pumping up well of polluted liquids should be emptied imperatively.
Filling the pump with compressed air is made through the upper section of the pump body in order to prevent the formation of air bubbles in the liquid.
The ductile sleeve is a material resistant to abrasion and temperatures in the order of 80xc2x0 C. and may also be resistant to different types of polluted liquids or exhibit all these qualities at the same time.
The pump body is cylindrical and corresponds, as regards its shape and/or its sizes, to the different diameters of the wells.
The length of the pump body corresponds to the main diameters of the wells, but is at least one meter, which enables to contain leachates or polluted liquids in the order of 4 or 5 liters.
For exemplification purposes, a pump body one meter long and with 80 mm useful diameter should contain 4-5 liters.
The operation pressure of the sleeve valve is determined by the limit pressure ensuring perfect tightness.
The maximum operation pressure of the compressed air in the pump body is smaller by 1.5 to 2 bars than that used in the sleeve valve. Thus, for exemplification purposes, for an 8-bar guaranteed sleeve valve, the operation pressure must not exceed 6-6.5 bars. With a pressure in the order of 6-6.5 bars, the device enables low flow rate pumping, in the order of 0 to 10 m3 per day, which corresponds to most applications. Such a pressure in the pump body enables pumping up liquids over a total pumping up height of approximately 60 to 65 meters, for liquids whose density is close to 1.
In order to protect the compressed air supply pipe of the sleeve valve against possible damages caused by the friction against the wall of the well, three embodiment variations have are foreseen. According to the first one, the pipe is integrated into the body of the pump, according to the second, it is placed along the pump body outside the said, and according to the third embodiment, a protection chute is fastened against the pump body and the pipe is placed inside the chute.
This chute can also receive wires connected to level slaving contacts. These contacts determine a signal that authorises stopping or re-starting the pump, according to the level of liquid in the well.
The presence of a chute also enables insertion of a pipe of xe2x80x98bubble-to-bubblexe2x80x99-type fluid level detection device.
Stepping several contacts along the pump body enables generating stepped signals supplying the operator with a hydric balance of the well, at the time considered.
The major interest of the pneumatic pumping device according to the invention lies in that it is totally explosion-proof and that, combined with several electrodes implanted corrected at distances defined along the chute or along the pump body, for example every five, ten or twenty centimeters, it also enables obtaining, at any moment, by periodic or continuous reading of these signals, the level and the variations, of the liquid levels in the well or the pit.